Ethical standards for obtaining competent informed consent require that a potential participant is able to express a choice concerning research participation. Standards further require that the individual is capable of appreciating, understanding, and reasoning through information pertaining to the research protocol. These capacities may be impaired in individuals with neurologic illness. In particular, owing to the presence of neuropsychological impairment, some patients with multiple sclerosis (M.S.) may have difficulty making competent decisions concerning research participation. Yet, this issue has heretofore not been addressed. Accordingly, the proposed project will evaluate performance of people with M.S. on a measure that is used to assess decision-making ability regarding research participation. It will also evaluate what aspects of neuropsychological function predict decision making with regard to research participation. Finally, it will examine whether cueing and repetition of research-related information improves decisional capacity regarding research participation. Individuals with M.S. and control participants will be administered a battery of standard neuropsychological tests that will emphasize executive function, memory, attention, and expressive and receptive language. Participants will then be presented with a standardized fictional research protocol that has previously been used to examine competency to provide informed consent, namely the MacArthur Competence Assessment Tool - Clinical Research (MacCAT-CR). The MacCAT-CR will assess ability to express a choice concerning research participation as well as ability to appreciate, understand, and reason through informed consent disclosures. Subsequently, information concerning the fictional research protocol will be repeated and cued, and participants' ability to appreciate, understand, and reason through the material will be re-assessed as will their capacity to express a choice. Performance on the neuropsychological test battery will be used to stratify participants according to severity of neurobehavioral deficit (participant groups: control group, M.S. unimpaired, M.S. mildly impaired, M.S. moderately-severely impaired). A one-way MANOVA (participant groups) will be used to compare MacCAT-CR performance across groups, specifically choice expression, understanding, appreciation, and reasoning about informed consent disclosures. Regression analyses will be employed to examine what aspects of neuropsychological function predict these same MacCAT-CR scores. To evaluate the effects of repetition and cueing on MacCAT-CR choice expression, understanding, appreciation, and reasoning scores, a mixed factor MANOVA will be conducted, and the resulting design will be a 4 (participant group: control group, M.S. unimpaired, M.S. mildly impaired, M.S. moderately-severely impaired) X 2 (time: pre-recognition cueing, post-recognition cueing) with time being a repeated factor. In addressing these issues, the proposed research will imply which M.S. patients are at greatest risk of making incompetent decisions to participate in research, and it may provide an effective method of remediating this difficulty. Overall, the long-term goal of this research is to ensure that research participants with M.S. are treated in an ethical manner.